Sound-reproducing device



June 25, 1929.

M. R. HUTCHISON 1.718.356

SOUND 'REPRODUCING DEVICE Filed April 29, 1927 INVENTOR.

Miller Reese Hull/1150!? ATTORNEY v 59 changes or other conditions of use.

QORPUEATIGN this Application filed April as, t

. This inventionrelates to sound reproduo ers and more particularly to reproducers of the electromechanical t pe in which a mechanical diaphragm is operated hy an elec- 5 tromagnetic unit. In order to insure an accurate and und1storted reproduction of sound in an apparatus of the above type, it is essential to maintain a fixed predeterminedspacing between D excessive stresses from being set up within the elements themselves.

This is acc omplishedfin accordance with the present invention by mountirn the tilements on a yieldable support so that any variations in the stress of the link connect-- ing the armature to the diaphragmwill air tomatically be relieved by movement of the entire unit. Excessive-stresses are therefore prevented from being set up within the electromagnetic unit or in the element connecting said unit to the diaphragm whereby any variations due to deformation, shock, temperature changes, or other causes Wlll be automatically compensated for and prevented from producing strains or disturbing the spacing of the various parts.

The stationary portion of the electromag :netic reproducing unit such as the pole pieces may be yieldably supported on a fixed framework and the vibrating element or armature may be operatively connected to the diaphragm by any suitable means. The

stationary portions are constructed so as tov have a moment of inertia sulliciently great ,to prevent movement thereof at r.udio frequencies in response to the usual operating forces and should have a free period-of vibration at a frequency below audihility whereby movement at audible frequencies will be still further opposed. Vibrations at these frequencies are thus executed practically entirely by the armature and transmitted thereby to the diaphragm. The unit is however, freely movable in response to applied shocks and consequently will automatically take up any stresses which'may be'introduced into the parts either by shocks, warping of the diaphragm, temperature The invention is particularly applicable to loud speaking devices having comparatively large diaphragms such as the so-called cone type loud speaker, but may however. be

"e the armature and pole pieces and to prevent applied to other cases where is desire 3 to vibrate a legible diaphragm, electrome :9 may talre the form ot a netic means which polarized relay or a push pull type resuch as those common used in telereceivers. Such rel ye are convJucted with a vibrating a: dare which is connected to the flexible di "agnc by a suitable lint: whereby the vihi .tions of the armature may. be to the dim phragm. g r,

The invention also consists in certain new original features of construct-ion comhinations of parts hereinafter set forth and claimed.

Although the novel features which are believed to be characteristic of this invention will he specifically pointed out in the claim appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of its organization, may be better understood by referring to the following description taken in connection with the accompanying drawing forming a part thereof, in which like reference characters have been used to denote like parts in the various figures. Since such illustration is, however, primarily for purposes of disclosure, it will be understood that the structure and the method of opera lieu thereof may be modified in various respects Without departing from the broad spirit and scope of the invention.

One embodiment of the invention has been shown for purposes of illustration in the accompanying drawing, in which Fig. l is a diagrammatic view of the re producing device constructed in accordance with this invention; and

Fig. 2 is an enlarged detail view of the unit and flexible support, and

Fig. 3 shows the invention cone type loud speaker. I

In the following description and in the claim the various details of the apparatus and the various steps in the process will he identified by specific means for convenience, but they are intended to be as generic in their application as the art will permit.

Referring to the figures more in detail, the invention is shown as'comprising a diaphragm 10 which'is capable of vibrating at audio frequencies, and is attached by suitable means to fixed supports 11. An elecapplied to a tromagnetic reproducing unit 1Q which may be of any well known form such as for example that having a movable armature and stationary-pole pieces, the details of construction thereof forming no part of the present invention, is rigidly secured to a mass 13 which may constitute a separate metallic block or may be included'as a part of the stationary portion o-f the'unit. It has been shown as a separate element for purposes of illustration only. Thennit 12 may be supported by a flexible member 14 from a support 11, the flexible member providing for'relative movement between the unit and the support. The movable element or armature'of unit 12 may be connected to diaphragm 10 by suitable means, such as link. 15

whereby thevibrations of the armature are transmitted to and reproduced by the diaphragm itself.

, The mass of'the stationary portion of the unit or pole pieces should ,be such that its moment of inertia is sufiiciently large to prevent movement thereof at audio frequencies in response to applied impulses and to cause such movement to be executed by the diav phragm. Furthermore, the natural period of vibration of the electromagnetic unit should be at a frequency below audibility.

Any warping of the diaphragm,'therefore-, which takes place slowly will cause a correspending movement of the unit due to the flexurc of the link 14, and any mechanical variations in the size of the parts due to changes in temperature will also be compensated for by the same means without imposing an excessive stress upon link 15; Furthermore, any jars or shocks, which would tendnto distort the various parts will cause a simultaneous movement of the unit and diaphragm and prevent injury to either element. v I

In the reproduction of sound Waves, the armature of electromagnetic relay 12 will be vibrated in response to the applied varying electric current of various audio frequencies. The moment of inertia of the pole pieces will prevent movement in response to such audio frequency vibrationsand will cause such vibrations to be transferred through link 15 to diaphragm 10. It is obvious, therefore, that the size of mass 13 must be such that it will be more difficult to cause floud speaker of well known'construction comprising a standard 20 and movable diaphragm 21 attached thereto. The elements corresponding to those in Fig. l are given similar reference numerals and operate in a 5111111111" manner.

Link 15 in this case is however, shown as connecting the armature of unit 12 with theapex of coneshaped diaphragm 21. v

In accordance with the present invention any distortion of the diaphragm or. of the support will be immediately compensated for without injury to any of the elements by movement of the electromagnetic unit. The adjustment of the diaphragm with respect to the pole pieces, therefore, having once been determined upon maybe maintained constant, and the stress upon link 15 may be prevented from increasing to an undesirable value. The size of the parts may, therefore, be reduced and the danger of damage in handling may be practically@aliminated.

Furthermore, a better tonal quality is insured inasmuch as the adjustment of the armature is not altered nor unusual stresses set up therein.

WVhile certain novel features of the invention have been shown and described and are pointed out in the annexed claim, it

will be understood, that various omissions,

substitutions and changes in the forms and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. i

What is claimed is A sound propagating device comprising a diaphragm, a retaining structure for saiddiaphragm, an actuating unit for said diaphragm and flexible means for supporting said actuating unit from said retaining struc ture Signed at-New York in the county of New ,York and State of New York this 28 day of April A. D. 1927.

MILLER REESE HUTGHISON. 

